Absorption and safety of rectally administered phenytoin

Parenteral phenytoin solution (Dilantin) was given rectally three times a day for three days to two beagle dogs. This was well tolerated, with no evidence of mucosal irritation noted either on endoscopic nor on rectal mucosal biopsy. When given in this manner, phenytoin is absorbed to a limited degree in canines. Parenteral phenytoin solution can be safely administered rectally, despite a pH of 12. Further study in normal volunteers is needed to assess the usefulness of this route of administration in situations in which the oral and/or parenteral route of administration is unavailable.